1. Field of Invention
The present invention relates to a navigation device and its navigation method, and in particular to a navigation device and its navigation method which dynamically adjust the displaying position of the current position and the displaying scale of the map in a navigation information frame according to current traveling direction of a navigation device.
2. Related Art
With the popularization of navigation device, more and more people start carrying the portable navigation device (PND). According to the positioning signals transmitted by the satellites of Global Positioning System (GPS), the navigation device retrieves the current position of the navigation device itself and displays a section the navigation map in a proper scale corresponding to the current position. A navigation route from the current position and to a destination set by a user is generated and displayed by the navigation device, and the navigation instruction required is also provided by the navigation device. The navigation device can also provide further information relevant to certain locations (points of interest, POI) on the navigation map and these information could relate to the various aspects of our daily life, such as living, transportation, travel and recreation, thus providing great convenience for the daily life of the user due to its portable design of light weight, compact size, and thin profile.
Take the navigation function of the vehicle navigation device as an example. In case that a user intends to travel from position A (current position) to position B (destination), and desires to know the optimal route from position A to position B (namely, the navigation route). Then, all the user has to do is to enter the position of the position B (destination) into a navigation device, then the navigation device will retrieve the position A (current position) through GPS at first and determine an optimal route from A to B through a navigation route planning function. The optimal route along with current position (which is changed with the movement of the navigation device) it is displayed in a navigation information frame in a display/screen of a navigation device. Such a navigation function assists the user to find out the roads in a stranger area.
FIG. 3A to FIG. 3C show the navigation information frames provided by a navigation device in the prior art. As above-mentioned, after the user set the destination 32, the navigation device generates a navigation route 34 from the current position 30 to the destination 32, and displays the navigation route 34 along with a section of a navigation map in a navigation information frame in a display/screen of the navigation device, as shown in FIG. 3A. The user will see the summary of all the navigation routes 34 at first, and then the navigation device enters into the navigation mode. Usually, the ordinary navigation information frame is zoomed in to show the current position 30, a part of the navigation route 34, and the corresponding displayed section of the navigation map in an enlarged proportional scale as shown in FIG. 3B. The user can realize the moving direction of the current position 30 on the route 34, and he/she can also read points of interest around current position 30 in corresponding displayed section of the navigation map. As the user proceed to the destination 30 along with the navigation device, the navigation device may generates real-time a traveling direction icon 36 according to the relations of between the current position 30 and the navigation route 34, for indicating the user to follow the navigation route 34 to the destination 32.
Referring to FIG. 3C, in the prior art, the current position 30 is displayed at the center of the navigation information frame. That is, the displayed part of navigation route 34 and corresponding displayed section of the navigation map take the current position 30 as the center. 50% of the corresponding displayed section of the navigation map is shown on the left side of the current position 30, and the other 50% are shown right side. Similarly, 50% of the navigation map is shown upside and downside of the current position 30 respectively. This manner for displaying the navigation map result in that the rest of the navigation route 34 displayed on the display/screen is limited while the part been followed-up of the navigation route 34 are still displayed on the display/screen. For example, as shown in FIG. 3B, in case that the traveling direction icon 36 indicates a straight forward direction (toward the upper side of a navigation information frame), and in this condition, only 50% (the upper portion) of the navigation information frame is used to show the rest of the navigation route 34, the other 50% (the lower portion) of the navigation information frame is still occupied by the part been followed-up of the navigation route 34 (which part is not required in navigation) (as shown in FIG. 3c). As such, in the navigation involving much more complicated navigation route 34, in particular, in the application of vehicle navigation device, the user may be misled to take the wrong route and direction for not being able to know more rest of the navigation routes 34 in advance, and even more seriously, it could adversely affected the driving safety of the vehicle.